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Prevent constant mux outputs from confusing itself.

This commit is contained in:
steve 2006-11-12 01:20:45 +00:00
parent 04ef0b7d80
commit c1333a21ef
1 changed files with 33 additions and 10 deletions
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43
cprop.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CVS_IDENT
#ident "$Id: cprop.cc,v 1.47.2.5 2006/04/23 04:26:13 steve Exp $"
#ident "$Id: cprop.cc,v 1.47.2.6 2006/11/12 01:20:45 steve Exp $"
#endif
# include "config.h"
@ -899,6 +899,14 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
return;
}
/* Create a temporary net to hold the result value that we
build up. When we are done, we will connect this to the
Result pins of the mux, then delete the mux *and* this
net. That will cause all the proper connectivity to
happen. */
NetNet result_tmp(scope, scope->local_symbol(),
NetNet::WIRE, obj->width());
/* We know that every slice has at least one constant. Run
through the slices again, creating boolean devices to
replace the MUX slice. */
@ -912,7 +920,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::BUFIF1);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,1), tmp->pin(1));
connect(obj->pin_Sel(0), tmp->pin(2));
des->add_node(tmp);
@ -926,7 +934,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::BUFIF0);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,0), tmp->pin(1));
connect(obj->pin_Sel(0), tmp->pin(2));
des->add_node(tmp);
@ -937,6 +945,15 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
the data inputs are both constant, and neither are
HiZ. From this we know how to generate the output
from only the S input. */
if (! (obj->pin_Data(idx, 0).nexus()->drivers_constant()
&& obj->pin_Data(idx, 1).nexus()->drivers_constant())) {
cerr << obj->get_line() << ": internal error: "
<< "Drivers not constant where expected?"
<< " obj->width()=" << obj->width()
<< " idx=" << idx
<< endl;
obj->dump_node(cerr, 4);
}
assert(obj->pin_Data(idx, 0).nexus()->drivers_constant()
&& obj->pin_Data(idx, 1).nexus()->drivers_constant());
@ -945,12 +962,12 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
verinum::V b = obj->pin_Data(idx, 1).nexus()->driven_value();
if (a == b) {
connect(obj->pin_Result(idx), obj->pin_Data(idx,0));
connect(result_tmp.pin(idx), obj->pin_Data(idx,0));
continue;
}
if (a == verinum::V0 && b == verinum::V1) {
connect(obj->pin_Result(idx), obj->pin_Sel(0));
connect(result_tmp.pin(idx), obj->pin_Sel(0));
continue;
}
@ -958,7 +975,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
2, NetLogic::NOT);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Sel(0), tmp->pin(1));
des->add_node(tmp);
continue;
@ -969,7 +986,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::AND);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,1), tmp->pin(1));
connect(obj->pin_Sel(0), tmp->pin(2));
des->add_node(tmp);
@ -981,7 +998,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::OR);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,0), tmp->pin(1));
connect(obj->pin_Sel(0), tmp->pin(2));
des->add_node(tmp);
@ -1003,7 +1020,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::OR);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,1), tmp->pin(1));
connect(inv->pin(0), tmp->pin(2));
des->add_node(tmp);
@ -1025,7 +1042,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::AND);
connect(obj->pin_Result(idx), tmp->pin(0));
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,0), tmp->pin(1));
connect(inv->pin(0), tmp->pin(2));
des->add_node(tmp);
@ -1036,6 +1053,9 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
}
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1)
connect(result_tmp.pin(idx), obj->pin_Result(idx));
delete obj;
count += 1;
}
@ -1316,6 +1336,9 @@ void cprop(Design*des)
/*
* $Log: cprop.cc,v $
* Revision 1.47.2.6 2006/11/12 01:20:45 steve
* Prevent constant mux outputs from confusing itself.
*
* Revision 1.47.2.5 2006/04/23 04:26:13 steve
* Constant propagate addresses through NetRamDq read ports.
*